I don’t know why Contis should be different from Lycos, for the GAMI injector benefit.
Yes; GAMIs will reduce roughness if the engine was bad to start with, but if you take any engine deep into the LOP region, the power variation between cylinders will become more pronounced and eventually some will “flame out”.
I have never seen any measurable improvement in MPG, by flying LOP, versus flying at peak EGT. So I have been flying at peak EGT ever since I got the plane in 2002. Had two engines stripped down and both were in an excellent condition in the relevant respects. For turbo engines, especially some like the PA46 installation, LOP can have specific benefits.
Some time ago I wrote up some notes.
If you fly peak EGT or slightly LOP, you can expect to improve MPG by maybe 10%, versus some “quite ROP” setting. Versus full-rich, probably 30-50%.
Thanks Peter, I had read all of your notes.
Gami had started their STC with Contis and almost all of the fuel saving reports are about Contis.
Very occasionally did I see any specific numbers regarding Lycoming engines (in terms of range extension when flying LOP with Gamijectors).
gildnn wrote:
I actually meant before and after the GAMIjector installation when flying LOP.
My consideration/goal is extending the range.
Well, if you are already running LOP today (even if a bit “roughly”), then you can’t extend your range eny more. You could only extend it by running less power.
gildnn wrote:
Then I must have misunderstood something. I thought roughness would come from the difference between the cylinders being “fed” unevenly, the so-called Gami-spread, i.e. some cylinders running LOP, others at peak EGT and some possibly ROP. I understood Gamijectors were supposed to narrow this spread and hence take away some of the “roughness”.
You should really read Mixture Magic to understand better. Mixtures will never be 100% the same in each single cylinder. And on the lean side, the power output of all cylinders will be less uniform, since the power curve (=power output as a function of fuel flow) is steeper than on the rich side.
An aircraft am looking at is going into pre-buy, more info after I get pre-buy results. It has the original Alcor single probe EGT, fuel flow and CHT, but no multi cylinder engine analyser.
Am planning to fit GAMI injectors but no engine analyser, leaning using the Alcor, engine smoothness and FF. This was standard practice for many years before the fashion for more colourful engine analysers. The aircraft would be on an engine oil trend analysis programme.
This article from the guru of LOP, Mike Busch, is quite interesting on what exactly the engine analysers are measuring:
https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2010-10_egt-myths-debunked.pdf
EAA_2010_10_egt_myths_debunked_pdf
I would strongly recommend to install an engine monitor.
It’s not only about being LOP or ROP but it’s a great safety feature.
You are able to detect failing valve, spark plug, lost compression, overheating, detonation or preignition in a single cylinder and to take appropriate action immediately.
Without that you are flying “blind”. That Alcor – you mentioned – gives you light on one cylinder only which – very often – has completely different parameters than other three or five.
There is a large labour content in installing a 6 cylinder engine monitor. JPI quote 45hrs and I would say that is for an experienced shop. You would be up around the £6-7k mark for it inc vat and things like making new hoses for the fuel flow transducer. Fitting the oil pressure sensor requires some planning. You also need to remove a magneto and retime it for the rpm sensor.
EGT and CHT is what really matters.
I would skip FF, oil press, RPM. You don’t really need those.
Then it’s just a half of that labour.
RobertL18C wrote:
Am planning to fit GAMI injectors but no engine analyser
That doesn’t make much sense. AFAIK, you really can’t do that anyway. Installing GAMIs requires fine tuning them, but you can’t do that if you don’t know the single EGTs/peaks.
Even if you could, having an engine monitor is more valuable than having the GAMIs. Some aircraft run quite OK LOP with stock injectors.
@boscomantico good points, single probe EGT and CHT with standard injectors it is.
@Raven would agree in a turbocharged engine a multi probe engine monitor is good insurance. For a de rated normally aspirated engine that will operate below 65% when leaned, I would rather spend the money on preventive maintenance and oil analysis.
